Investigators have speculated that endocrinologic and metabolic changes associated with menopause, interact with or accelerate events of normal aging, to promote increased incidence of metabolic bone disease, heart disease, diabetes, hypertension, breast cancer, osteoarthritis, autoimmune disease, and menstrual bleeding disorders at the mid-life (45- 50 years). We will test to determine if menopausal-related changes in hormones or menstrual cycle patterns are associated with changes in joints indicative of arthritis development, loss of bone density, and change in body composition. Additionally, we propose to compare the information gathered from the 300 African-American women in the proposed study with comparable information currently being gathered from 582 white pre- and preimenopausal women and funded as an RO-1. We propose to measure 300 pre- perimenopausal African-American women, and 200 caucasian women aged 40-50 years at baseline in 1994 and aged 45-55 years at final contact 5 years later. Using annual hormone measurements, timed to the menstrual cycle, and monthly menstrual calendars, we will identify changes in reproductive hormone levels (e.g., estrogen, follicle stimulating hormone and testosterone) and menstrual cycle patterns (including abnormal bleeding). Measurements will be made of bone density (by dual x-ray densitometry (DEXA)), hand and knee joints (x-rays), body composition (DEXA), and blood pressure. A subgroup of women with atypical menstrual cycle lengths will be asked to collect urine daily through two menstrual cycles. The urine samples will be analyzed for reproductive hormones as explanatory factors of substantial difference in cycle lengths.